Albumin localization in rat liver parenchymal cells

In this study, we re-investigated the localization of albumin in hepatocytes using immunocytochemistry (ICC) on ultrathin cryo-sections of rat livers, which were immersion or perfusion-fixed with paraformaldehyde or a mixture of paraformaldehyde and glutaraldehyde. The sections were indirectly labelled with rhodamine-conjugated IgG or with 8 nm protein A-colloidal gold particles. We demonstrate that perfusion-fixation is obligatory for a proper localization of albumin. After perfusion fixation, all hepatocytes of fed and fasted rats were uniformly labelled. At the subcellular level albumin was localized in hepatocytes in the membrane-bound compartments of the entire secretory pathway, i.e. the rough and smooth ER, peripheral Golgi vesicles, all Golgi cisternae and the secretory granules. Concentration of albumin appeared mainly to occur at the cis-Golgi side.